Invalid or Badly Formatted MDN

An AS2 receipt contains a MIME multipart/report with a human-readable message and a message/disposition-notification part. A signed receipt wraps that report and a signature in multipart/signed, as defined in RFC 4130.

Open the returned MDN in the AS2 Logs. Check its MIME headers and boundaries, then the disposition-notification fields. For example, a successful disposition can contain:

Original-Message-ID: <message-id-from-the-original-transmission>
Disposition: automatic-action/MDN-sent-automatically; processed
Received-Content-MIC: <digest-of-the-original-message>, sha-256

This is an illustrative fragment, not a complete MDN. The message ID and Message Integrity Check (MIC) must correspond to the original transmission.

A message such as "The AS2 message has been received successfully" is only the human-readable portion. Correct MIME formatting and reassuring text do not establish a valid receipt. Files.com applies the partner's MDN validation level to the MIC, disposition, signature, and certificate as applicable.

Some partner systems return an HTML error page or raw processing error instead of an MDN. Give your trading partner the returned error, HTTP status, transmission time, and message ID so they can investigate the endpoint or downstream processing failure. If the structure is valid but signature validation fails, see Incorrectly Signed MDN.